Especially in the aircraft industry, it is becoming desirable that electronic control units, or "black boxes," each comprise a housing containing essentially a single circuit panel or mother board to which are electrically connectable a plurality of line replaceable modules on one surface and shipboard electrical systems on the other. Each line replaceable module, or LRM, performs a control or sensing or recording function and comprises essentially one or more circuit cards or daughter boards loaded with various electrical and electronic components, mounted to a heat sink plate and protected and shielded by cover plates, such as is disclosed in U.S. patent application Ser. No. 07/078/944 filed July 28, 1987 and assigned to the assignee hereof. The LRM is intended to be a durable, rugged assembly capable of being handled and repeatedly inserted into and removed from a black box for testing, repair, modification or replacement.
The plurality of LRMs are closely spaced in a side by side array within the black box and along the mother board; and each LRM has a small dimension along the array to facilitate such close spacing. The daughter card or cards and all of the electrical and electronic components connected thereto necessary in the LRM are secured to a heat sink plate disposed essentially along a plane transverse to the array of LRMs and extending rearwardly from the LRM connector at the forward end of the LRM, so that the LRM is long rearwardly and is wide transverse to the array. The electrical connector mounted on the forward end thereof has a mating face exposed to mate with the mating face of a corresponding one of a plurality of electrical connectors secured on the mother board mounted within the black box in a closely spaced array for efficient use of the real estate of the mother board. The black box must be provided with guiding means along opposing side walls extending from the LRM-receiving opening to each other board connector, to guide the long and wide LRM into lateral and axial alignment with the respective mother board connector for proper aligned mating of the connectors.
In one particular design of black box the guide means for each LRM comprises a pair of opposed channels formed in and along surfaces of plate members mounted along the side walls of the black box, and the cover plates of each LRM form a flange along each of its opposed side edges to be disposed in the guide channels therefor. The LRM flange is dimensioned just thin enough to permit movement along the channel without permitting side to side movement, for vibration resistance. Due to practical considerations the mother board with its precisely located circuitry cannot be mounted in the black box in such a way that its connectors are precisely aligned with the channels associated therewith which are already formed in the plate members of the black box. Therefore, the channel locations are not particularly precisely located with respect to the mother board connectors; the LRM flanges are constrained to move therealong which results in the LRM also being not particularly precisely aligned with the respective mother board connector. As a result, for this particular black box design either the mother board connector or the LRM connector must be capable of incremental lateral movement during mating to provide precise alignment of their terminals prior to terminal engagement.
Rack and panel or drawer connectors are known wherein one of a mating pair includes integral alignment posts extending forwardly therefrom to enter corresponding apertures of the other, for connector self-aligning during mating. At least one of the mating connectors is float mounted either on a panel or on framework or a panel at the leading end of the drawer by shoulder screws through enlarged diameter holes through connector flanges, enabling incremental lateral movement caused by bearing engagement of the alignment posts and apertures. Such a connector is the METRIMATE Drawer Connector (trademark of AMP Incorporated, Harrisburg, Pa.); another is disclosed in U.S. Pat. No. 4,647,130; and in both the connectors contain terminals terminated to discrete conductors. However, the float mounting means of the prior art drawer connectors is not particularly suitable for either the mother board connector or the LRM connector, which in turn means that the alignment post and aperture arrangement thereof also is not suitable for use with LRMs.
Mother board connectors in the black box must be fixedly mounted to the mother board to protect the terminations of those of its terminals which are soldered to circuit paths of the board, and the LRM connector must be secured well enough to and within the cover plates of the LRM to protect the terminations of those of its terminals which are soldered to circuit paths of daughter cards fixedly secured to heat sink plates within the LRM. Each mating pair of the plurality of electrical terminals of the connectors across their mating faces must be precisely aligned to establish respective electrical connections therebetween; the connectors may also have optical fiber connectors similarly requiring precise alignment for establishing optical connections. One type of high density connector which can be adapted for use in an LRM is diclosed in U.S. Pat. No. 4,715,829.
In U.S. patent application Ser. No. 07/078,944, the terminal housing means of the LRM connector is recessed within a shroud at the forward end of the LRM and is secured within the cover plates against axial movement but is permitted incremental lateral movement within a peripheral gap around the inside shroud surface. An alignment rib extends forwardly from the LRM connector housing means to enter a corresponding aperture in the mother board connector, and upon bearing engagement urges the LRM connector housing means incrementally laterally to align therewith.
It is desired to provide a guide means which is particularly precisely located and aligned with respect to the particular mother board connector with which the connector of an LRM is to mate, whereby the LRM is itself particularly precisely aligned with the mother board connector, and the connector housing of the LRM need not move incrementally within the LRM to align with the mother board connector, permitting an LRM of simpler construction and assembly.